Tropical and Boreal Forest – Atmosphere Interactions: A Review

Paulo Artaxo; Hans-Christen Hansson; Meinrat O. Andreae; Jaana Bäck; Eliane Gomes Alves; Henrique M. J. Barbosa; Frida Bender; Efstratios Bourtsoukidis; Samara Carbone; Jinshu Chi; Stefano Decesari; Viviane R. Després; Florian Ditas; Ekaterina Ezhova; Sandro Fuzzi; Niles J. Hasselquist; Jost Heintzenberg; Bruna A. Holanda; Alex Guenther; Hannele Hakola; Liine Heikkinen; Veli-Matti Kerminen; Jenni Kontkanen; Radovan Krejci; Markku Kulmala; Jost V. Lavric; Gerrit de Leeuw; Katrianne Lehtipalo; Luiz Augusto T. Machado; Gordon McFiggans; arco Aurelio M. Franco; Bruno Backes Meller; Fernando G. Morais; Claudia Mohr; William Morgan; Mats B. Nilsson; Matthias Peichl; Tuukka Petäjä; Maria Praß; Christopher Pöhlker; Mira L. Pöhlker; Ulrich Pöschl; Celso Von Randow; Ilona Riipinen; Janne Rinne; Luciana V. Rizzo; Daniel Rosenfeld; Maria A. F. Silva Dias; Larisa Sogacheva; Philip Stier; Erik Swietlicki; Matthias Sörgel; Peter Tunved; Aki Virkkula; Jian Wang; Bettina Weber; Ana Maria Yáñez-Serrano; Paul Zieger; Eugene Mikhailov; James N. Smith; Jürgen Kesselmeier
2022 | TELLUS B | 74 (24-163)

This review presents how the boreal and the tropical forests affect the atmosphere, its chemical composition, its function, and further how that affects the climate and, in return, the ecosystems through feedback processes. Observations from key tower sites standing out due to their long-term comprehensive observations: The Amazon Tall Tower Observatory in Central Amazonia, the Zotino Tall Tower Observatory in Siberia, and the Station to Measure Ecosystem-Atmosphere Relations at Hyytiäla in Finland. The review is complemented by short-term observations from networks and large experiments.

The review discusses atmospheric chemistry observations, aerosol formation and processing, physiochemical aerosol, and cloud condensation nuclei properties and finds surprising similarities and important differences in the two ecosystems. The aerosol concentrations and chemistry are similar, particularly concerning the main chemical components, both dominated by an organic fraction, while the boreal ecosystem has generally higher concentrations of inorganics, due to higher influence of long-range transported air pollution. The emissions of biogenic volatile organic compounds are dominated by isoprene and monoterpene in the tropical and boreal regions, respectively, being the main precursors of the organic aerosol fraction.

Observations and modeling studies show that climate change and deforestation affect the ecosystems such that the carbon and hydrological cycles in Amazonia are changing to carbon neutrality and affect precipitation downwind. In Africa, the tropical forests are so far maintaining their carbon sink.

It is urgent to better understand the interaction between these major ecosystems, the atmosphere, and climate, which calls for more observation sites, providing long-term data on water, carbon, and other biogeochemical cycles. This is essential in finding a sustainable balance between forest preservation and reforestation versus a potential increase in food production and biofuels, which are critical in maintaining ecosystem services and global climate stability. Reducing global warming and deforestation is vital for tropical forests.

Synergistic HNO3-H2SO4-NH3 upper tropospheric particle formation

Wang, MY; Xiao, M; Bertozzi, B; Marie, G; Rorup, B; Schulze, B; Bardakov, R; He, XC; Shen, JL; Scholz, W; Marten, R; Dada, L; Baalbaki, R; Lopez, B; Lamkaddam, H; Manninen, HE; Amorim, A; Ataei, F; Bogert, P; Brasseur, Z; Caudillo, L; De Menezes, LP; Duplissy, J; Ekman, AML; Finkenzeller, H; Carracedo, LG; Granzin, M; Guida, R; Heinritzi, M; Hofbauer, V; Hohler, K; Korhonen, K; Krechmer, JE; Kurten, A; Lehtipalo, K; Mahfouz, NGA; Makhmutov, V; Massabo, D; Mathot, S; Mauldin, RL; Mentler, B; Muller, T; Onnela, A; Petaja, T; Philippov, M; Piedehierro, AA; Pozzer, A; Ranjithkumar, A; Schervish, M; Schobesberger, S; Simon, M; Stozhkov, Y; Tome, A; Umo, NS; Vogel, F; Wagner, R; Wang, DS; Weber, SK; Welti, A; Wu, YS; Zauner-Wieczorek, M; Sipila, M; Winkler, PM; Hansel, A; Baltensperger, U; Kulmala, M; Flagan, RC; Curtius, J; Riipinen, I; Gordon, H; Lelieveld, J; El-Haddad, I; Volkamer, R; Worsnop, DR; Christoudias, T; Kirkby, J; Mohler, O; Donahue, NM
2022 | Nature | 605 (7910) (483-+)

Tropical and Boreal Forest Atmosphere Interactions: A Review

Artaxo, P; Hansson, HC; Andreae, MO; Back, J; Alves, EG; Barbosa, HMJ; Bender, F; Bourtsoukidis, E; Carbone, S; Chi, JS; Decesari, S; Despres, VR; Ditas, F; Ezhova, E; Fuzzi, S; Hasselquist, NJ; Heintzenberg, J; Holanda, BA; Guenther, A; Hakola, H; Heikkinen, L; Kerminen, VM; Kontkanen, J; Krejci, R; Kulmala, M; Lavric, JV; de Leeuw, G; Lehtipalo, K; Machado, LAT; McFiggans, G; Franco, MAM; Meller, BB; Morais, FG; Mohr, C; Morgan, W; Nilsson, MB; Peichl, M; Petaja, T; Prass, M; Pohlker, C; Pohlker, ML; Poschl, U; Von Randow, C; Riipinen, I; Rinne, J; Rizzo, LV; Rosenfeld, D; Dias, MAFS; Sogacheva, L; Stier, P; Swietlicki, E; Sorgel, M; Tunved, P; Virkkula, A; Wang, J; Weber, B; Yanez-Serrano, AM; Zieger, P; Mikhailov, E; Smith, JN; Kesselmeier, J
2022 | Tellus Ser. B-Chem. Phys. Meteorol. | 74 (1) (24-163)

Contribution of traffic-originated nanoparticle emissions to regional and local aerosol levels

Olin, M; Patoulias, D; Kuuluvainen, H; Niemi, JV; Ronkko, T; Pandis, SN; Riipinen, I; Dal Maso, M
2022 | Atmos. Chem. Phys. | 22 (2) (1131-1148)

Insights into the molecular composition of semi-volatile aerosols in the summertime central Arctic Ocean using FIGAERO-CIMS

Siegel, K.; Karlsson, L.; Zieger, P.; Baccarini, A.; Schmale, J.; Lawler, M.; Salter, M.; Leck, C.; Ekman, A.; Riipinen, I.; Mohr, C.
2021 | Environ. Sci. Atmos. | 1 (4) (161-175)

The remote central Arctic during summertime has a pristine atmosphere with very low aerosol particle concentrations. As the region becomes increasingly ice-free during summer, enhanced ocean-atmosphere fluxes of aerosol particles and precursor gases may therefore have impacts on the climate. However, large knowledge gaps remain regarding the sources and physicochemical properties of aerosols in this region. Here, we present insights into the molecular composition of semi-volatile aerosol components collected in September 2018 during the MOCCHA (Microbiology-Ocean-Cloud-Coupling in the High Arctic) campaign as part of the Arctic Ocean 2018 expedition with the Swedish Icebreaker Oden. Analysis was performed offline in the laboratory using an iodide High Resolution Time-of-Flight Chemical Ionization Mass Spectrometer with a Filter Inlet for Gases and AEROsols (FIGAERO-HRToF-CIMS). Our analysis revealed significant signal from organic and sulfur-containing compounds, indicative of marine aerosol sources, with a wide range of carbon numbers and O : C ratios. Several of the sulfur-containing compounds are oxidation products of dimethyl sulfide (DMS), a gas released by phytoplankton and ice algae. Comparison of the time series of particulate and gas-phase DMS oxidation products did not reveal a significant correlation, indicative of the different lifetimes of precursor and oxidation products in the different phases. This is the first time the FIGAERO-HRToF-CIMS was used to investigate the composition of aerosols in the central Arctic. The detailed information on the molecular composition of Arctic aerosols presented here can be used for the assessment of aerosol solubility and volatility, which is relevant for understanding aerosol–cloud interactions.

Photolytically induced changes in composition and volatility of biogenic secondary organic aerosol from nitrate radical oxidation during night-to-day transition

Wu, C; Bell, DM; Graham, EL; Haslett, S; Riipinen, I; Baltensperger, U; Bertrand, A; Giannoukos, S; Schoonbaert, J; El Haddad, I; Prevot, ASH; Huang, W; Mohr, C
2021 | Atmos. Chem. Phys. | 21 (19) (14907-14925)
alpha-pinene , carbonyl nitrates , chemical composition , evaporation kinetics , isoprene oxidation , mass-spectrometer , model , no3 , optical-properties , photolysis

Night-time reactions of biogenic volatile organic compounds (BVOCs) and nitrate radicals (NO3) can lead to the formation of NO3-initiated biogenic secondary organic aerosol (BSOANO(3)). Here, we study the impacts of light exposure on the chemical composition and volatility of BSOANO(3) formed in the dark from three precursors (isoprene, alpha-pinene, and beta-caryophyllene) in atmospheric simulation chamber experiments. Our study represents BSOANO(3) formation conditions where reactions between peroxy radicals (RO2 + RO2) and between RO2 and NO3 are favoured. The emphasis here is on the identification of particle-phase organonitrates (ONs) formed in the dark and their changes during photolytic ageing on timescales of similar to 1 h. The chemical composition of particle-phase compounds was measured with a chemical ionization mass spectrometer with a filter inlet for gases and aerosols (FIGAERO-CIMS) and an extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF). Volatility information on BSOANO(3) was derived from FIGAERO-CIMS desorption profiles (thermograms) and a volatility tandem differential mobility analyser (VTDMA). During photolytic ageing, there was a relatively small change in mass due to evaporation (< 5 % for the isoprene and alpha-pinene BSOANO3, and 12 % for the beta-caryophyllene BSOANO(3)), but we observed significant changes in the chemical composition of the BSOANO(3). Overall, 48 %, 44 %, and 60 % of the respective total signal for the isoprene, alpha-pinene, and beta-caryophyllene BSOANO(3) was sensitive to photolytic ageing and exhibited decay. The photolabile compounds include both monomers and oligomers. Oligomers can decompose into their monomer units through photolysis of the bonds (e.g. likely O-O) between them. Fragmentation of both oligomers and monomers also happened at other positions, causing the formation of compounds with shorter carbon skeletons. The cleavage of the nitrate functional group from the carbon chain was likely not a main degradation pathway in our experiments. In addition, photolytic degradation of compounds changes their volatility and can lead to evaporation. We use different methods to assess bulk volatilities and discuss their changes during both dark ageing and photolysis in the context of the chemical changes that we observed. We also reveal large uncertainties in saturation vapour pressure estimated from parameterizations for the ON oligomers with multiple nitrate groups. Overall, our results suggest that photolysis causes photodegradation of a substantial fraction of BSOANO(3), changes both the chemical composition and the bulk volatility of the particles, and might be a potentially important loss pathway of BSOANO(3) during the night-to-day transition.

Steady-State Mass Balance Model for Predicting Particle-Gas Concentration Ratios of PBDEs

2021 | Environ. Sci. Technol. | 55 (14) (9425-9433)
air partition-coefficients , aromatic-hydrocarbons pahs , brominated flame retardants , dibenzo-p-dioxins , diphenyl ethers pbdes , equilibration time scales , global air , long range transport , semivolatile organic-chemicals , vapor-pressure
Assuming equilibrium partitioning between the gas and particle phases has been shown to overestimate the fraction of low-volatility chemicals in the particle phase. Here, we present a new steady-state mass balance model that includes separate compartments for fine and coarse aerosols and the gas phase and study its sensitivity to the input parameters. We apply the new model to investigate deviations from equilibrium partitioning by exploring model scenarios for seven generic aerosol scenarios representing different environments and different distributions of emissions as the gas phase, fine aerosol, and coarse aerosol. With 100% of emissions as the particle phase, the particle-gas concentration ratio in our model is similar to the equilibrium model, while differences are up to a factor of 10(6) with 100% of emissions as the gas phase. The particle-gas concentration ratios also depend on the particle size distributions and aerosol loadings in the different environmental scenarios. The new mass balance model can predict the particle-gas concentration ratio with more fidelity to measurements than equilibrium models. However, further laboratory-based evaluations and calibrations of the standard sampling techniques, field investigations with preferably size-resolved measurements of aerosol particle composition, together with the appropriate process modeling for low-volatility chemicals are warranted.

Transport and chemistry of isoprene and its oxidation products in deep convective clouds

Bardakov, R; Thornton, JA; Riipinen, I; Krejci, R; Ekman, AML
2021 | Tellus Ser. B-Chem. Phys. Meteorol. | 73 (1)
convective transport of isoprene , deep convective cloud trajectories , epoxide formation , gas-phase , ice , particle formation , photochemical box model , photolysis frequencies , rain forest , secondary organic aerosol , thermodynamic model , tropical upper troposphere , united-states
Deep convective clouds can transport trace gases from the planetary boundary layer into the upper troposphere where subsequent chemistry may impact aerosol particle formation and growth. In this modelling study, we investigate processes that affect isoprene and its oxidation products injected into the upper troposphere by an isolated deep convective cloud in the Amazon. We run a photochemical box model with coupled cloud microphysics along hundreds of individual air parcel trajectories sampled from a cloud-resolving model simulation of a convective event. The box model simulates gas-phase chemical reactions, gas scavenging by liquid and ice hydrometeors, and turbulent dilution inside a deep convective cloud. The results illustrate the potential importance of gas uptake to anvil ice in regulating the intensity of the isoprene oxidation and associated low volatility organic vapour concentrations in the outflow. Isoprene transport and fate also depends on the abundance of lightning-generated nitrogen oxide radicals (NOx = NO + NO2). If gas uptake on ice is efficient and lightning activity is low, around 30% of the boundary layer isoprene will survive to the cloud outflow after approximately one hour of transport, while all the low volatile oxidation products will be scavenged by the cloud hydrometeors. If lightning NOx is abundant and gas uptake by ice is inefficient, then all isoprene will be oxidised during transport or in the immediate outflow region, while several low volatility isoprene oxidation products will have elevated concentrations in the cloud outflow. Reducing uncertainties associated with the uptake of vapours on ice hydrometeors, especially HO2 and oxygenated organics, is essential to improve predictions of isoprene and its oxidation products in deep convective outflows and their potential contribution to new particle formation and growth.

The importance of Aitken mode aerosol particles for cloud sustenance in the summertime high Arctic – a simulation study supported by observational data

Bulatovic, I; Igel, AL; Leck, C; Heintzenberg, J; Riipinen, I; Ekman, AML
2021 | Atmos. Chem. Phys. | 21 (5) (3871-3897)
The potential importance of Aitken mode particles (diameters similar to 25-80 nm) for stratiform mixed-phase clouds in the summertime high Arctic (> 80 degrees N) has been investigated using two large-eddy simulation models. We find that, in both models, Aitken mode particles significantly affect the simulated microphysical and radiative properties of the cloud and can help sustain the cloud when accumulation mode concentrations are low (< 10-20 cm(-3)), even when the particles have low hygroscopicity (hygroscopicity parameter - kappa = 0.1). However, the influence of the Aitken mode decreases if the overall liquid water content of the cloud is low, either due to a higher ice fraction or due to low radiative cooling rates. An analysis of the simulated supersaturation (ss) statistics shows that the ss frequently reaches 0.5 % and sometimes even exceeds 1 %, which confirms that Aitken mode particles can be activated. The modelling results are in qualitative agreement with observations of the Hoppel minimum obtained from four different expeditions in the high Arctic. Our findings highlight the importance of better understanding Aitken mode particle formation, chemical properties and emissions, particularly in clean environments such as the high Arctic.

Molecular Perspective on Water Vapor Accommodation into Ice and Its Dependence on Temperature

Daniel Schlesinger; Samuel J. Lowe; Tinja Olenius; Xiangrui Kong; Jan B. C. Pettersson; Ilona Riipinen
2020 | JOURNAL OF PHYSICAL CHEMISTRY A | 124 (51) (10879-10889)

The Roles of the Atmosphere and Ocean in Driving Arctic Warming Due to European Aerosol Reductions

Krishnan, S; Ekman, AML; Hansson, HC; Riipinen, I; Lewinschal, A; Wilcox, LJ; Dallafior, T
2020 | Geophys Res Lett | 47 (7)
Clean air policies can have significant impacts on climate in remote regions. Previous modeling studies have shown that the temperature response to European sulfate aerosol reductions is largest in the Arctic. Here we investigate the atmospheric and ocean roles in driving this enhanced Arctic warming using a set of fully coupled and slab-ocean simulations (specified ocean heat convergence fluxes) with the Norwegian Earth system model (NorESM), under scenarios with high and low European aerosol emissions relative to year 2000. We show that atmospheric processes drive most of the Arctic response. The ocean pathway plays a secondary role inducing small temperature changes mostly in the opposite direction of the atmospheric response. Important modulators of the temperature response patterns are changes in sea ice extent and subsequent turbulent heat flux exchange, suggesting that a proper representation of Arctic sea ice and turbulent changes is key to predicting the Arctic response to midlatitude aerosol forcing. Plain Language Summary Aerosols are liquid or solid particles suspended in air, which may have adverse air quality and health impacts. Sulfate aerosols also have a cooling influence on climate and can mask some of the greenhouse gas-induced global warming. While aerosol emissions are variable in space and time, their impacts are not limited to where they are emitted. In fact, studies using global climate models have shown that changing sulfur dioxide emissions in Europe can have significant impacts on Arctic climate. Here we investigate the roles of changes in atmospheric and ocean heat transport in driving these changes in the Arctic by conducting a series of climate model simulations with specified anthropogenic sulfur dioxide emissions and different ocean heat transport fluxes. We find that changes through the atmosphere play a primary role in affecting the Arctic climate. These changes are modulated by changes in sea ice extent and the energy exchange between ocean and atmosphere in the sub-Arctic. Aerosol-driven changes in ocean heat transport play a smaller, secondary role in the Arctic and tend to reduce the impacts. Our results show that the proper representation of Arctic sea ice is crucial for accurately modeling the Arctic response to changes in midlatitude aerosol forcing.

Open questions on atmospheric nanoparticle growth

Yli-Juuti, T; Mohr, C; Riipinen, I
Cloud droplets form in the atmosphere on aerosol particles, many of which result from nucleation of vapors. Here the authors comment on current knowledge and open questions regarding the condensational growth of nucleated particles to sizes where they influence cloud formation.

Contact information

Visiting addresses:

Geovetenskapens Hus,
Svante Arrhenius väg 8, Stockholm

Arrheniuslaboratoriet, Svante Arrhenius väg 16, Stockholm (Unit for Toxicological Chemistry)

Mailing address:
Department of Environmental Science
Stockholm University
106 91 Stockholm

Press enquiries should be directed to:

Stella Papadopoulou
Science Communicator
Phone +46 (0)8 674 70 11